Vitamin D wasn’t always known to be essential to healthy living. It took the prevalence of disease and a scientific narrowing of causes to discover it. Today much more is known about the value of vitamin D in human diets. By discovering vitamin D, researchers improved the lives of people around the world.
At the turn of the 20th century in western countries, it was believed the average diet should be 12 percent protein, 5 percent mineral, up to 30 percent fat, and up to about 50 percent carbohydrates.1 As can be seen, there is a heavy reliance on fats, proteins, and carbohydrates, with little focus on vitamins.
Couple this diet with poor working and living conditions for the lower class, and it is not surprising that many people were extremely deficient in vitamin D.
Such deficiencies lead to rickets, a condition in which the bones soften because there is a lack of vitamin D to help calcify them.2 As a result, the legs often bowed outward, and there were known to pain in the pelvis, spine, and legs.5
During the Industrial Revolution, poor children working in factories were most vulnerable to rickets.3 They often worked up to 14 hours a day, seven days a week. In addition to the dangers of being around large, heavy equipment, these children never were outside long enough to soak up the sun’s rays.
Discovery of vitamin D
Sir Edward Mellanby, a British researcher, came to be credited with some of the first discoveries of the nature of vitamin D. He fed dogs kept exclusively indoors a diet high in oatmeal, similar to that found in Scotland at the time. The result was that the dogs developed rickets.1
Mellanby correctly deducted that some substance in the oatmeal diet was linked to rickets. He found that cod liver oil cured the rickets, so assumed that vitamin A was responsible.
Elmer McCollum and Marguerite Davis, American researchers, were interested in Mellanby’s findings. McCollum and Davis had previously discovered vitamin A, and by bubbling oxygen through cod liver oil, they were able to destroy the oil’s vitamin A. The oil still managed to cure rickets with vitamin A removed, and he was able to definitively determine is was not vitamin A but a new substance. They called it vitamin D.1
By the 1950s, most people thought that rickets had pretty well been eliminated, but in Canada there was a marked increase in cases of vitamin D deficiency seen in hospitals after fortification of milk was stopped. The government promptly re-introduced milk fortification.4
In Great Britain, an outbreak of hypercalcemia, or too much vitamin D, led the government to strictly reduce vitamin D fortification only to cereals and margarine.4 Research for determining the correct doses of vitamin D for adults, children, and infants is ongoing.
Today’s vitamin D
Symptoms of vitamin D deficiency today include metabolic disorders, cancer, cardiovascular disease, autoimmune diseases, infections, depression, and cognitive disorders.6
All milk sold in the United States and Canada is now voluntarily fortified with vitamin D. Other foods often fortified include margarine and yogurt, and most Americans get their vitamin D intake from fortified foods.7
In today’s modern, industrialized society, it is often too easy to assume that vitamin-enriched foods have always been there. The truth is, as with any other scientific discovery, it takes time to make all the connections necessary to understand how vitamins affect our body. This is certainly the case with vitamin D.